Current intravascular sensing devices require calibration and anticoagulants to be infused over the sensor and into the patient's vasculature. Ex-vivo systems require lengthy tubing runs to pull blood away from the patient and the blood must go through numerous valves to prevent calibrants and anticoagulants to be administered to the patient. Many of the ex-vivo systems also require sampled blood to be disposed of via a waste system and not returned to a patient. Sensor systems may therefore undesirably administer volumes of anticoagulants and calibration solutions to patients and/or may temporarily or permanently remove large blood volumes from the patient.